/*========================== begin_copyright_notice ============================

Copyright (C) 2017-2021 Intel Corporation

SPDX-License-Identifier: MIT

============================= end_copyright_notice ===========================*/

#include "Compiler/CISACodeGen/LivenessAnalysis.hpp"
#include "Compiler/CISACodeGen/ShaderCodeGen.hpp"
#include "Compiler/CISACodeGen/LiveVars.hpp"
#include "Compiler/CodeGenPublic.h"
#include "Compiler/IGCPassSupport.h"
#include "common/debug/Debug.hpp"
#include "common/igc_regkeys.hpp"
#include "common/LLVMWarningsPush.hpp"
#include "llvm/ADT/SparseBitVector.h"
#include <llvm/IR/CFG.h>
#include <llvm/ADT/DenseMap.h>
#include <llvm/ADT/SmallVector.h>
#include <llvm/IR/DataLayout.h>
#include <llvm/IR/InstIterator.h>
#include <llvm/IR/Instructions.h>
#include <llvm/IR/InstIterator.h>
#include "common/LLVMWarningsPop.hpp"
#include "Probe/Assertion.h"

using namespace llvm;
using namespace IGC;

char LivenessAnalysis::ID = 0;

std::string LivenessAnalysis::getllvmValueName(Value *V) {
  if (V->hasName()) {
    return std::string(V->getName());
  }
  // For unamed value, try the following:
  std::string Str;
  raw_string_ostream aOS(Str);
  aOS << *V;
  Str = aOS.str();
  // Name starting with %
  int bid = Str.find_first_of('%');
  int end = Str.find_first_of(' ', bid);
  std::string vname = Str.substr(bid, end - bid);
  return vname;
}

// Register pass to igc-opt
#define PASS_FLAG "igc-livenessanalysis"
#define PASS_DESCRIPTION "Calculate liveness based on LiveVars"
#define PASS_CFG_ONLY false
#define PASS_ANALYSIS true
IGC_INITIALIZE_PASS_BEGIN(LivenessAnalysis, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)
// IGC_INITIALIZE_PASS_DEPENDENCY(LiveVarsAnalysis)
IGC_INITIALIZE_PASS_END(LivenessAnalysis, PASS_FLAG, PASS_DESCRIPTION, PASS_CFG_ONLY, PASS_ANALYSIS)

// runOnFunction set up Map only. calculate() computes Liveness.
bool LivenessAnalysis::runOnFunction(Function &F) {
  m_F = &F;

  // Pre-allocate memory to avoid many small alocations.
  // todo: reuse it from LiveVars
  size_t nVals = m_F->arg_size();
  for (auto &BB : *m_F) {
    nVals += BB.size();
  }

  // We will allocate a bit more (~10%) in case it needs expansion.
  // Also, as llvm::DenseMap will resize if the Map's capacity is 75% full,
  // allocate even more to avoid such automatic resizing.
  uint32_t mapCap1 = int_cast<uint32_t>((size_t)(nVals * 1.40f));
  uint32_t vecCap1 = int_cast<uint32_t>((size_t)(nVals * 1.10f));
  ValueIds.grow(mapCap1);
  IdValues.reserve(vecCap1);

  initValueIds();

  return false;
}

LivenessAnalysis::~LivenessAnalysis() { clear(); }

void LivenessAnalysis::clear() {
  KillInsts.clear();
  ValueIds.clear();
  IdValues.clear();
  BBLiveIns.clear();

  delete m_LV;
  m_LV = nullptr;
}

void LivenessAnalysis::initValueIds() {
  int ix = 0;
  for (Function::arg_iterator AI = m_F->arg_begin(), AE = m_F->arg_end(); AI != AE; ++AI) {
    Value *Val = &*AI;
    ValueIds.insert(std::make_pair(Val, ix));
    IdValues.push_back(Val);
    ++ix;
  }

  for (inst_iterator II = inst_begin(m_F), IE = inst_end(m_F); II != IE; ++II) {
    Instruction *Inst = &*II;
    ValueIds.insert(std::make_pair(Inst, ix));
    IdValues.push_back(Inst);
    ++ix;
  }
}

void LivenessAnalysis::setLiveIn(BasicBlock *BB, Value *V) {
  ValueToIntMap::iterator I = ValueIds.find(V);
  if (I == ValueIds.end()) {
    return;
  }
  int id = I->second;
  setLiveIn(BB, id);
}

inline void LivenessAnalysis::setLiveIn(BasicBlock *BB, int ValueID) {
  SBitVector &BV = BBLiveIns[BB];
  BV.set(ValueID);
}

inline void LivenessAnalysis::setKillInsts(Value *V, Instruction *kill) {
  ValueVec &VS = KillInsts[kill];
  VS.push_back(V);
}

bool LivenessAnalysis::isInstLastUseOfValue(Value *V, Instruction *I) {
  ValueVec &VS = KillInsts[I];
  for (int i = 0, e = (int)VS.size(); i < e; ++I) {
    if (VS[i] == V) {
      return true;
    }
  }
  return false;
}

bool LivenessAnalysis::isBefore(Instruction *A, Instruction *B) {
  IGC_ASSERT(nullptr != A);
  IGC_ASSERT(nullptr != B);
  IGC_ASSERT_MESSAGE(A->getParent() == B->getParent(), "A and B must be within the same BB!");

  int nA = (int)getDistance(A);
  int nB = (int)getDistance(B);
  return nA < nB;
}

void LivenessAnalysis::calculate(Function *F) {
  // If m_LV is not nullptr, it means that the full liveness has been
  // computed. No need to recompute and just return.
  if (m_LV) {
    return;
  }

  // Since we re-calculate, make sure to begin with a clean
  // state. Note that ValueIds are not cleared here, as we
  // want to make sure ValueIds are valid as long as this
  // analysis is valid.  If we re-calculate value ids, a value
  // might be assigned a different id than the one assigned
  // by runOnFunction.
  KillInsts.clear();
  BBLiveIns.clear();

  m_F = F;
  m_WIA = getAnalysisIfAvailable<WIAnalysis>();

  // todo: might use LiveVars as a pass
  m_LV = new LiveVars();
  m_LV->Calculate(F, m_WIA);

  // Pre-allocate memory to avoid many small alocations.
  size_t nVals = IdValues.size();

  // We will allocate a bit more (~10%) in case it needs expansion.
  // Also, as llvm::DenseMap will resize if the Map's capacity is 75% full,
  // allocate even more to avoid such automatic resizing.
  uint32_t mapCap1 = int_cast<uint32_t>((size_t)(nVals * 1.40f));
  uint32_t mapCap2 = int_cast<uint32_t>((size_t)(m_F->size() * 1.40f));
  BBLiveIns.grow(mapCap2);
  KillInsts.grow(mapCap1);

  for (LiveVars::iterator LVI = m_LV->begin(), LVE = m_LV->end(); LVI != LVE; ++LVI) {
    Value *V = LVI->first;
    LiveVars::LVInfo *lvi = LVI->second;
    ValueToIntMap::iterator VI = ValueIds.find(V);
    if (VI == ValueIds.end()) {
      // Only value in ValueIds are considered.
      continue;
    }
    int valID = VI->second;

    // V is either an instruction or an argument. If defBB is nullptr,
    // V is an argument; otherwise, it is the defining BB.
    BasicBlock *defBB = nullptr;
    if (Instruction *defInst = dyn_cast<Instruction>(V)) {
      defBB = defInst->getParent();
    }

    for (auto II = lvi->AliveBlocks.begin(), IE = lvi->AliveBlocks.end(); II != IE; ++II) {
      BasicBlock *BB = *II;
      setLiveIn(BB, valID);
    }

    for (std::vector<Instruction *>::iterator II = lvi->Kills.begin(), IE = lvi->Kills.end(); II != IE; ++II) {
      Instruction *inst = *II;
      setKillInsts(V, inst);

      // If inst's BB isn't "V"'s defBB, V must be live into this BB.
      // This condition check also works when "V" is an argument.
      BasicBlock *useBB = inst->getParent();
      if (defBB != useBB) {
        setLiveIn(useBB, valID);
      }
    }
  }

  if (IGC_IS_FLAG_ENABLED(EnableLivenessDump)) {
    print(errs());
  }
}

void LivenessAnalysis::print_livein(raw_ostream &OS, BasicBlock *BB) {
  SBitVector &BitVec = BBLiveIns[BB];
  OS << "    Live-In-Values (#values = " << BitVec.count() << " ):\n";

  SBitVector::iterator I, E;
  int nVals = 0;
  for (I = BitVec.begin(), E = BitVec.end(); I != E; ++I) {
    int id = *I;
    Value *V = IdValues[id];
    IGC_ASSERT_MESSAGE(nullptr != V, "Value should be in Value Map!");
    if (nVals == 0) {
      OS << "      ";
    }
    if (V->hasName()) {
      OS << V->getName() << ",  ";
    } else {
      OS << getllvmValueName(V) << ",  ";
    }
    ++nVals;
    if (nVals == 8) {
      // 8 values per line
      OS << "\n";
      nVals = 0;
    }
  }
  OS << "\n\n";
}

void LivenessAnalysis::print(raw_ostream &OS) {
  if (!m_F)
    return;

  std::stringstream ss;
  ss << "LivenessAnalysis: " << m_F->getName().str();
  Debug::Banner(OS, ss.str());

  for (Function::iterator I = m_F->begin(), E = m_F->end(); I != E; ++I) {
    BasicBlock *BB = &*I;
    OS << "BB:";
    if (BB->hasName())
      OS << " " << BB->getName();
    OS << "       ; preds =";
    bool isFirst = true;
    for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
      BasicBlock *pred = *PI;
      OS << ((isFirst) ? " " : ", ");
      OS << (pred->hasName() ? pred->getName() : "Unamed(wrong)");
      isFirst = false;
    }
    OS << "\n";
    print_livein(OS, BB);
    for (BasicBlock::iterator it = BB->begin(), ie = BB->end(); it != ie; ++it) {
      Instruction *I = &*it;
      OS << *I << '\n';
    }
    OS << "\n";
  }
}

#if defined(_DEBUG)

void LivenessAnalysis::dump() { print(dbgs()); }

void LivenessAnalysis::dump_livein(BasicBlock *BB) { print_livein(dbgs(), BB); }

void LivenessAnalysis::dump_livein() {
  if (!m_F) {
    return;
  }

  for (auto &BI : *m_F) {
    BasicBlock &BB = BI;
    print_livein(dbgs(), &BB);
  }
}

#endif
